Grass trimming head and grass trimmer having the same

ABSTRACT

A grass trimming head includes a housing assembly and a spool. The housing assembly is formed with a housing cavity and an outer aperture for allowing a cutting line to be inserted from an outside of the housing assembly into the housing cavity. At least a portion of the spool is arranged inside the housing cavity, and the spool is rotatable with respect to the housing assembly about a central axis. The spool is formed with an inner aperture for allowing the cutting line to be inserted into the spool or a clamping portion configured to fix the cutting line.

RELATED APPLICATION INFORMATION

The present application claims the benefit of International ApplicationNumber PCT/CN2018/096413, filed on Jul. 20, 2018, through which thisapplication claims the benefit of Chinese Patent Application No.201720979787.X, filed on Aug. 7, 2017, and Chinese Patent ApplicationNo. 201720979716.X, filed on Aug. 7, 2017, each of which is incorporatedherein by reference in its entirety.

TECHNICAL FIELD

The present disclosure relates to a grass trimming head and a grasstrimmer having the same.

BACKGROUND

A grass trimmer is a gardening tool and used to trim the lawn. The grasstrimmer includes a grass trimming head. The grass trimming head isrotated at a high speed to drive a cutting line mounted on the grasstrimming head to rotate, realizing the cutting function.

The grass trimming head includes a spool allowing the cutting line to bewound thereon. During the cutting operation, the cutting ne is worn awaygradually due to wear. After operating for a period, it is needed tochange a new cutting line and wind the new cutting line around thespool. For the existing grass trimming head, the spool needs to bedisassembled to wind the cutting line around the spool. The windingmanner is time consuming and laborious, and the situation of blockingthe cutting line is more likely to occur.

SUMMARY

In order to solve the shortcomings of the related art, an object of thepresent disclosure is to provide a grass trimming head capable ofconveniently winding and a grass trimmer having the same.

In order to achieve this object, the technical scheme adopted by thepresent disclosure is as follows.

A grass trimming head, includes a housing and a spool. The housingassembly is formed with a housing cavity and provided with an outeraperture for allowing a cutting line to be inserted from an outside ofthe housing assembly into the housing cavity. At least a portion of thespool is arranged inside the housing cavity, and the spool is rotatablewith respect to the housing assembly about a central axis. And the spoolis provided with an inner aperture for allowing the cutting line to beinserted into the spool or a clamping portion configured to fix thecutting line.

In one example, the spool includes an upper spool portion and a lowerspool portion around. The first flange portion is connected to an upperend of the upper winding portion. The second flange portion is connectedto a lower end of the upper winding portion. The lower spool portionincludes a lower winding portion, a third flange portion and a fourthflange portion. The lower winding portion is configured for winding thecutting line. The third flange portion is connected to an upper end ofthe lower winding portion. And the fourth flange portion is connected toa lower end of the lower winding portion. The upper spool portion iscoupled to the lower spool portion to form a line guide passageconfigured for the cutting line passing through the spool.

In one example, the line guide passage extends along a curved line.

In one example, the upper spool portion is coupled to the lower spoolportion to form at least two line guide passages intersected with eachother.

In one example, the upper spool portion is coupled to the lower spoolportion to form three line guide passages. Any two of the three lineguide passages are intersected with each other, and the three line guidepassages are arranged around the central axis.

In one example, the housing assembly includes an upper housing and alower housing. The spool is arranged between the upper housing and thelower housing. The lower housing is provided with a protrusion portionprotruding towards the upper housing, and the lower spool portion isformed with a groove matched with the protrusion portion. And theprotrusion portion is matched with the groove to guide the housingassembly to move with respect to the spool along the central axis.

In one example, the grass trimming head further includes a bearing and aknocking cap. The protrusion portion is formed with a mounting groove.The bearing is arranged inside the mounting groove, and the bearing isconnected to the knocking cap and the lower housing.

In one example, the grass trimming head further includes a spring. Thegroove is arranged throughout the lower spool portion along the centralaxis. The spring protrudes out of the groove. The spring is arrangedbetween the upper spool portion and the lower housing, and configured toan acting force causing the upper spool portion and the lower housing togo away from each other.

In one example, the upper housing is formed with a first matching tooth.The spool is formed with a first engaging tooth matched with the firstmatching tooth, and the first engaging tooth is formed with an inclinedsurface.

In one example, the grass trimming head further includes an eyeletmember. The eyelet member is fixed to the housing assembly andconfigured for the cutting line passing out from the housing assembly.

In one example, the housing assembly includes a housing and an eyeletmember. The housing is formed with the housing cavity, and the eyeletmember is fixed to the housing and formed with the outer aperture. Thespool is formed with the inner aperture, and a distance from the eyeletmember to the spool is less than or equal to 3 mm.

In one example, the spool includes at least one winding portionconfigured for winding the cutting line and two flange portions arrangedat two ends of the at least one winding portion. The inner aperture isarranged on the at least two flange portions. And a distance from theeyelet member to each flange portion is less than or equal to 3 mm.

In one example, the eyelet member is formed with two bumps protrudingtowards the spool, and the two bumps are arranged on two sides of theouter aperture respectively.

In one example, the two bumps are arranged along a circumferentialdirection of the central axis.

In one example, the spool includes an upper winding portion, a lowerwinding portion, a middle flange portion, an upper flange portion, and alower flange portion. The upper winding portion is configured forwinding the cutting line. A lower winding portion is configured forwinding the cutting line. A middle flange portion is located between theupper winding portion and the lower winding portion and formed with theinner aperture for the cutting line to be inserted into An upper flangeportion is connected to an upper end of the upper winding portion. Andthe lower flange portion is connected to a lower end of the lowerwinding portion. The two bumps are located between an upper surface anda lower surface of the middle flange portion along the central axis.

In one example, the outer aperture is a waist-shaped hole. A size of theouter aperture along the central axis is defined as a height of theouter aperture. A size of the outer aperture along a directionperpendicular to the central axis is defined as a width of the outeraperture. A size of the outer aperture along an extending direction isdefined as a depth of the outer aperture. A distance between the twobumps is the same as the width of the outer aperture. And the width ofouter aperture is greater than the height of the outer aperture.

In one example, the eyelet member is formed with a notch on one side ofa projection of the eyelet member on a plane perpendicular to thecentral axis, the one side of the projection faces towards the spool.

In one example, a distance from the eyelet member to a flange portion isless than a maximum outer diameter of the cutting line.

In one example, the grass trimming head further includes a drivingmember configured to apply an acting force to the housing assembly orthe spool. The acting force causes the housing assembly and the spool torelatively rotate. The spool has a line loading position with respect tothe housing assembly. In condition that the spool is at the line loadingposition with respect to the housing assembly, the cutting line bedirectly inserted into the inner aperture or the clamping portion afterpassing through the outer aperture. The housing assembly is formed witha first positioning surface, and the spool is formed with a secondpositioning surface matched with the first positioning surface. Incondition that one of the spool and the housing assembly is rotated withrespect to another to cause the first positioning surface and the secondpositioning surface to be in contact, the spool is at the line loadingposition.

In one example, the driving member is a spring. The spring is arrangedbetween the housing assembly and the spool, and configured to apply theacting force to the spool or the housing assembly, and the acting forcecauses the first positioning surface and the second positioning surfaceto go towards each other.

In one example, the housing assembly is formed with a plurality of firstmatching teeth arranged around a circumferential direction of thecentral axis, and the spool is formed with a plurality of first engagingteeth matched with the plurality of first matching teeth. The spring isconfigured to apply the acting force to the spool or the housingassembly, and the acting force causes the first matching teeth and thesecond matching teeth to be in contact. Each of the first matching teethor the first engaging teeth is provided with an inclined surfaceinclined to a normal surface of the central axis. Each of the firstmatching teeth is formed with the first positioning surface, and each ofthe first engaging teeth is formed with the second positioning surface.A number of the first engaging teeth is the same as a number of innerapertures.

In one example, in condition that the first positioning surface is incontact with the second positioning surface, two sides of a matchingtooth is in contact with two adjacent first engaging teeth respectively.

In one example, each of the first matching teeth is formed with a firstinclined surface inclined to the normal surface of the central axis, andeach of the first engaging teeth is formed with a second inclinedsurface inclined to the normal surface of the central axis. The firstinclined surface and the first positioning surface are located on twosides of a respective matching tooth respectively, and the secondinclined surface and the second positioning surface are located on twosides of a respective engaging tooth respectively. In condition that thefirst positioning surface is in contact with the second positioningsurface, the first inclined surface is in contact with the secondinclined surface.

In one example, the spool includes an upper winding portion, a lowerwinding portion, a middle flange portion, an upper flange portion, and alower flange portion. The upper winding portion is configured forwinding the cutting line. The lower winding portion, configured forwinding the cutting line. The middle flange portion is located betweenthe upper winding portion and the lower winding portion and formed withthe inner aperture for the cutting line to be inserted into. The upperflange portion is connected to an upper end of the upper windingportion. And the lower flange portion is connected to a lower end of thelower winding portion. The first engaging teeth are arranged on theupper flange portion or the lower flange portion.

In one example, the housing assembly includes a housing and an eyeletmember. The housing is formed with the housing cavity. And the eyeletmember is fixed to the housing and formed with the outer aperture forthe cutting line passing through. At least a portion of the eyeletmember protrudes towards the spool, and a distance from the eyeletmember to the middle spool is less than or equal to 3 mm.

In one example, an even number of the first engaging teeth are provided.

In one example, an angle between the inclined surface and the normalsurface of the central axis is greater than or equal to 8 degrees, andless than or equal to 18 degrees.

In one example, the driving member is an elastic member. The elasticmember is connected to the spool and the housing assembly, andconfigured to apply the acting force to the spool or the housingassembly, and the acting force causes the first positioning surface andthe second positioning surface to go towards each other.

In one example, the driving member is a magnetic member. The magneticmember is connected to the spool and the housing assembly, andconfigured to apply the acting force to the spool or the housingassembly, and the acting force causes the first positioning surface andthe second positioning surface to go towards each other.

In one example, the magnetic member includes a first magnetic member anda second magnetic member. The first magnetic member is fixed to thespool, and the second magnetic member is fixed to the housing assembly.

In one example, the spool is formed with a plurality of line guidepassages for the cutting line passing throughout. The spool includes afirst piece and a second piece, and the first piece is coupled to thesecond piece to form the plurality of line guide passages.

In one example, at least two of projections of the plurality of the lineguide passages on a plane perpendicular to the central axis areintersected to each other.

In one example, the grass trimming head further includes a knocking cap.The knocking cap comprises a contact portion configured for contactingwith ground. And a ratio of a projection area of the contact portion ona plane perpendicular to the central axis to a projection area of thehousing assembly on the plane perpendicular to the central axis isgreater than or equal to 0.3, and less than or equal to 1.

In one example, a surface of the contact portion is a smooth curvedsurface.

In one example, the projection area of the contact portion on the planeperpendicular to the central axis has a circular shape.

In one example, a ratio of a maximum size of the contact portion in aradial direction of the central axis to a maximum size of the spool inthe radial direction of the central axis is greater than or equal to0.7, and less than or equal to 1.1.

In one example, the housing assembly includes an upper housing and alower housing. The knocking cap is rotatably connected to the lowerhousing.

In one example, the grass trimming head further includes a bearingconnected to the knocking cap and the lower housing.

In one example, the lower housing is provided with a protrusion portionprotruding towards the upper housing, and the spool is formed with agroove matched with the protrusion portion.

In one example, the protrusion portion is formed with a mounting groove,and the bearing is arranged inside the mounting groove.

In one example, the grass trimming head further includes a spring. Atleast a portion of the spring is arranged inside the groove, and thespring is connected to the lower housing and the spool.

In one example, the knocking cap is rotatably connected to the spool.

A grass trimmer, includes a grass trimming mechanism and an operationdevice. The grass trimming mechanism including a grass trimming headdescribed above and a motor configured to drive the grass trimming headto rotate. The operation device is configured for being operated by theuser to control the grass trimmer.

The advantage of the present disclosure is that the user can perform thewinding operation quickly and conveniently without disassembling thespool.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic view illustrating a grass trimmer.

FIG. 2 is a partial structural view illustrating a grass trimmer.

FIG. 3 is a schematic view illustrating a first housing of the grasstrimmer in FIG. 2.

FIG. 4 is a schematic view illustrating a working housing in FIG. 1.

FIG. 5 is an exploded view illustrating partial structures in FIG. 4.

FIG. 6 is a cross-sectional view illustrating a grass trimming head anda motor in FIG. 1.

FIG. 7 is an exploded view illustrating the grass trimming head and themotor in FIG. 1.

FIG. 8 is an exploded view illustrating the grass trimming head in FIG.7.

FIG. 9 is an exploded view illustrating the grass trimming head, themotor, and a grass trimming mechanism in FIG. 4.

FIG. 10 is an exploded view illustrating another perspective of thegrass trimming head, the motor, and the grass trimming mechanism in FIG.4.

FIG. 11A is a cross-sectional view illustrating a connecting pipe inFIG. 1.

FIG. 11B is a schematic view illustrating the connecting pipe in FIG.11A adding an embedded member.

FIG. 12 is a schematic view illustrating a knocking cap of the grasstrimming head in FIG. 6.

FIG. 13 is a schematic view illustrating an upper housing of the grasstrimming head in FIG. 9.

FIG. 14 is a schematic view illustrating a spool of the grass trimminghead in FIG. 9.

FIG. 15 is a schematic view illustrating another perspective of thespool in FIG. 14.

FIG. 16 is an exploded view illustrating the spool in FIG. 14.

FIG. 17 is an exploded view illustrating another perspective of thespool in FIG. 14.

FIG. 18 is a schematic view illustrating of the spool and the eyeletmember of the grass trimming head in FIG. 9.

FIG. 19 is schematic view illustrating an outlet string passage of thespool in FIG. 18

FIG. 20A is a schematic view illustrating the eyelet member of the grasstrimming head in FIG. 9.

FIG. 20B is a schematic view illustrating another perspective of theeyelet member in FIG. 20A.

FIG. 20C is a cross-sectional view illustrating the eyelet member inFIG. 20A.

FIG. 21A is a schematic view illustrating a first engaging tooth and afirst matching tooth of the grass trimming head in FIG. 8 sliding withrespect to each other.

FIG. 21B is a schematic view illustrating a first positioning surfaceand a second positioning surface in FIG. 21A being in contact.

FIG. 22 is a schematic view illustrating a grass trimming head includinga spool formed with a bump.

FIG. 23 is a schematic view illustrating the spool and a lower housingin FIG. 22.

FIG. 24 is a schematic view illustrating a housing being formed with abump.

FIG. 25 is a schematic view illustrating another spool.

FIG. 26 is an exploded view illustrating the spool in FIG. 25.

FIG. 27 is a schematic view illustrating another spool.

FIG. 28 is an exploded view illustrating the spool in FIG. 27.

FIG. 29 is an exploded view illustrating another perspective of thespool in FIG. 27.

FIG. 30 is a schematic view illustrating another grass trimming head.

FIG. 31 is an exploded view of another perspective of the grass trimminghead in FIG. 30.

FIG. 32 is a schematic view illustrating the spool of the grass trimminghead in FIG. 30.

FIG. 33 is a schematic view illustrating another grass trimming head.

FIG. 34 is an exploded view illustrating the grass trimming head in FIG.33.

FIG. 35 is a schematic view illustrating a first magnetic member and asecond magnetic member of the grass trimming head in FIG. 33.

FIG. 36 is a schematic view illustrating another perspective the firstmagnetic member and the second magnetic member of the grass trimminghead in FIG. 33.

FIG. 37 is a schematic view illustrating another grass trimming head.

FIG. 38 is an exploded view illustrating the grass trimming head in FIG.37.

FIG. 39 is a schematic view illustrating a grass trimming head and afriction member.

FIG. 40 is an exploded view illustrating the grass trimming head in FIG.39.

FIG. 41 is a schematic view illustrating a grass trimming head and astopping member.

FIG. 42 is an exploded view illustrating another perspective of thestopping member of the grass trimming head in FIG. 41.

FIG. 43 is a schematic view illustrating of a motor and a grass trimminghead.

FIG. 44 is a schematic view illustrating another grass trimmer.

FIG. 45 is a partial structural schematic view illustrating the grasstrimmer in FIG. 44.

FIG. 46 is a schematic view illustrating another perspective of thepartial grass trimmer in FIG. 45.

FIG. 47 is an exploded view of the partial grass trimmer in FIG. 45.

FIG. 48 is an exploded view of another perspective of the partial grasstrimmer in FIG. 45.

FIG. 49 is a schematic view illustrating another grass trimmer.

FIG. 50 is a partial structural schematic view illustrating the grasstrimmer in FIG. 49.

FIG. 51 is a schematic view illustrating a function switching member inFIG. 50 being at a second position.

FIG. 52 is a schematic view illustrating the function switching memberin FIG. 50 being at a first position.

DETAILED DESCRIPTION

Hereinafter the present disclosure will be described in detail inconjunction with accompanying drawings and examples.

As shown in FIG. 1 to FIG. 3, a grass trimmer 100 includes a motor 10,an operation device 20, a grass trimming mechanism 30 and a connectingpipe 40.

The operation device 20 is used for user's operation to control thegrass trimmer 100. In one example, the operation device 20 includes ahandle 21, a first switch 22 and a first operation member 23. The handle21 is used for being gripped by the user. The handle 21 includes ahandle housing 211. The first switch 22 is arranged inside the handlehousing 211. The handle housing 211 includes a left handle housing 211 aand a right handle housing 211 b. The first switch 22 is located betweenthe left handle housing 211 a and the right handle housing 211 b. Theconnecting pipe 40 is clamped by the left handle housing 211 a and theright handle housing 211 b from two sides of the connecting pipe 40. Inanother example, the grass trimmer 100 further includes an auxiliaryhandle 212. The auxiliary handle 212 is fixed to the connecting pipe 40.

The first operation member 23 is used for being operated by the user soas to control the first switch 22, when the handle 21 is gripped by theuser. The first switch 22 is electrically connected to the motor 10 andconfigured to control the motor 10. The first switch 22 may activate themotor 10 so that the grass trimmer 100 realizes the cutting function. Inanother example, the first switch 22 is further configured to control arotating speed of the motor 10. The first operation member 23 is atrigger. The operation device 20 further includes a locking member 24for preventing the first operation member 23 from being accidentallyactivated. When the locking member 24 is triggered, the first operationmember 23 can be operated by the user. The locking member 24 is atrigger. The first operation member 23 is rotatably connected to thehandle housing 211 about a first axis 103. The locking member 24 isrotatably connected to the handle housing 211 about a second axis 104.The first axis 103 is perpendicular to the second axis 104. Theconnecting pipe 40 extends along a first straight line 105. The firstaxis 103 is perpendicular to the first straight line 105. The secondaxis 104 is perpendicular to the first straight line 105. When thehandle 21 is gripped by the user, the locking member 24 may be triggeredby the thumb, and the first operation member 23 is triggered by theindex finger, so that the operation is convenient and comfortable.

As shown in FIG. 4 to FIG. 6, the grass trimming mechanism 30 is usedfor realizing the tooling function. The grass trimming mechanism 30includes a grass trimming head 50. The grass trimming head 50 is usedfor accommodating the cutting line 101. A portion of the cutting line101 protruding out of the grass trimming head 50 is driven by the grasstrimming head 50 to rotate so as to cut the vegetation. The motor 10 isconfigured to drive the grass trimming head 50 to rotate. The grasstrimming head 50 includes a spool 53 and a housing 52. The spool 53 isconfigured for being wound by the cutting line 101. At least a portionof the spool 53 is arranged within the housing 52.

As shown in FIG. 1 to FIG. 2, the connecting pipe 40 is connected to theoperation device 20 and the grass trimming mechanism 30. The connectingpipe 40 is connected to the grass trimming head 50 and a handle 21.

The grass trimmer 100 has an auto-winding mode and a cutting mode.

When the grass trimmer 100 is in the auto-winding mode, the spool 53,the housing 52 or the cutting line 101 do not need to be manuallyrotated, and the cutting line 101 can be automatically wound to thespool 53. In one example, when the grass trimmer 100 is in theauto-winding mode, the motor 10 drives at least one of the spool 53 andthe housing 52, so that the spool 53 and the housing 52 are relativelyrotated to automatically wind the cutting line 101 to the spool 53.

When the grass trimmer 100 is in the cutting mode, the motor 10 drivesthe spool 53 and the housing 52 to synchronously rotate, and the cuttingline 101 and the spool 53 remain relatively fixed, so that the motor 10drives the grass trimming head 50 to rotate so as to drive the cuttingline 101 to rotate, achieving the cutting of the vegetation.

As shown in FIG. 5 and FIG. 6, the grass trimming mechanism 30 furtherincludes a second switch 31 and a second operation member 32. The secondswitch 31 is electrically connected to the motor 10. The secondoperation member 32 is configured for being operated by the user tocontrol the second switch 31. The second switch 31 is configured tocontrol the motor 10 so that the grass trimmer 100 is in or enters theauto-winding mode. The motor 10 drives at least one of the spool 53 andthe housing 52 so that the spool 53 and the housing 52 are relativelyrotated to automatically wind the cutting line 101 to the spool 53. Thefirst switch 22 is configured to control the motor 10 so that the grasstrimmer 100 is in or enters the cutting mode. The motor 10 drives thespool 53 and the housing 52 to synchronously rotate so as to drive thecutting line 101 to rotate to cut the vegetation.

In one example, when the grass trimmer 100 is in the auto-winding mode,a rotating speed of the spool 53 is greater than or equal to 100 rpm,and less than or equal to 2000 rpm. In one example, the rotating speedof the spool 53 is greater than or equal to 200 rpm, and less than orequal to 800 rpm. In another example, the rotating speed of the spool 53is greater than or equal to 30 rpm, and less than or equal to 600 rpm.Or the rotating speed of the spool 53 is greater than or equal to 60rpm, and less than or equal to 300 rpm. A ratio of a rotating speed ofthe spool 53 in the cutting mode to a rotating speed of the spool 53 inthe auto-winding mode is greater than or equal to 5, and less than orequal to 300. In another example, the ratio of the rotating speed of thespool 53 in the cutting mode to the rotating speed of the spool 53 inthe auto-winding mode is greater than or equal to 10, and less than orequal to 200.

As shown in FIG. 4, FIG. 5, FIG. 9 and FIG. 10, the grass trimmingmechanism 30 further includes a working housing 33. The working housing33 is configured for connecting each component of the grass trimmingmechanism 30 to be a whole. In one example, the working housing 33includes a switch housing 331 and a motor housing 332. The switchhousing 331 and the motor housing 332 may be a whole or may be twoseparate detachable components. In one example, the switch housing 331is configured to fix and accommodate the second switch 31. The motorhousing 332 is configured to accommodate or mount the motor 10. Theswitch housing 331 is fixed to the motor housing 332. The workinghousing 33 is connected to one end of the connecting pipe 40. In oneexample, the motor housing 332 is fixed to the one end of the connectingpipe 40, and the switch housing 331 is connected to the one end of theconnecting pipe 40. The connecting pipe 40 is arranged throughout theswitch housing 331. The switch housing 331 includes a first switchhousing 331 a and a second switch housing 331 b. The first switchhousing 331 a and the second switch housing 331 b are arranged on twosides of the connecting pipe 40. The motor 10 and grass trimming head 50are arranged on a same end of the connecting pipe 40. The motor islocated inside the working housing 33.

In another example, the motor is arranged on one end of the connectingpipe facing away from the grass trimming head, that is, the motor is notlocated inside the working housing.

A shield 70 plays a role of safety protection, and prevents the cuttingline 101 from causing damages to the user. In one example, the shield 70is fixed to the working housing 33. In one example, the shield 70 isfixed to the motor housing 332. At least a portion of the switch housing331 is located between the motor housing 332 and the shield 70. In oneexample, the shield is fixed to the connecting pipe.

The second operation member 32 is adjacent to the grass trimming head50. After the cutting line 101 and the spool 53 are combined, the secondoperation member 32 may be directly operated by the user to activate theautomatic winding function. The first operation member 23 is arrangedaway from the grass trimming head 50. When the user grips the handle 21to perform the cutting operation, the user can be away from the grasstrimming head 50 to avoid the occurrence of the damages. The firstoperation member 23 and the second operation member 32 are away fromeach other. The first operation member 23 and the second operation 32are arranged on two ends of the connecting pipe 40, so that the user isunable to touch the second operation member 32 when operating the firstoperation member 23, and the user is also unable to touch the firstoperation member 23 when operating the second operation member 32, whicheffectively avoids the damages caused by the housing where one operationmember is accidentally touched when another operation member is operatedby the user.

The second operation member 32 and the second switch 31 are located ontwo sides of the connecting pipe 40. In one example, the second switch31 is arranged below the connecting pipe 40, and the second operationmember 32 is arranged above the connecting pipe 40. The grass trimminghead 50 and the second operation member 32 are located on the two sidesof the connecting pipe 40. The second operation member 32 is locatedabove the connecting pipe 40 and away from the grass trimming head 50 toprevent the cutting line 101 from causing damages to the human body whenthe second operation member 32 is operated by the user. An angled areais formed by the motor housing 332 and the connecting pipe 40. In otherwords, the angled area is formed by the grass trimming head 50 and theconnecting pipe 40. The second switch 31 is located within the angledarea. The angled area realizes the protection on the second switch 21and prevents the second switch 31 from touching the ground to causedamages. The manner that the second operation member 32 and the secondswitch 31 are located on the two sides of the connecting pipe 40 alsoavoids the problem of excessive volume caused by the second operationmember 32 and the second switch 31 being located on the same side of theconnecting pipe 40.

As shown in FIG. 2 and FIG. 3, the grass trimmer 100 further includes acircuit board 65, a first housing 60 and a battery pack 66. The circuitboard 65 is electrically connected to the first switch 22, andelectrically connected to the second switch 31. The circuit board 65 isaccommodated by the first housing 60. The circuit board 65 iselectrically connected to the motor 10 and the battery pack 66 so thatthe battery pack 66 supplies power to the motor 10 and controls themotor 10.

The first housing 60 is formed with a first chamber 64 for accommodatingthe circuit board 65. The motor housing 332 is formed with a secondchamber 333 for accommodating the motor 10. The connecting pipe 40 has ahollow tubular structure. The connecting pipe 40 is formed with anairflow passage 47 for communicating the first chamber 64 with thesecond chamber 333. Cooling airflow can pass through the airflow passage47 to communicate the first chamber 64 with the second chamber 333 so asto cool the motor 10 and the circuit board 65.

The grass trimmer 100 includes a guide wire 49. The guide wire 49 iselectrically connected to the battery pack 66 and the motor 10. Theguide wire 49 is located inside the connecting pipe 40.

In one example, the first housing and the handle housing may be a whole.When the first housing and the handle housing is a whole, it should beunderstood that the whole may be described to be the first housing ormay be described to be the handle housing.

The battery pack 66 may be detachably connected to the first housing 60.The first housing 60 is fixed to another end of the connecting pipe 40.In one example, the first housing 60 and the motor housing 332 arerespectively fixed to the two ends of the connecting pipe 40.

In one example, the grass trimmer includes a cable wire. The cable wireis connected to the battery pack or commercial power.

In one example, the grass trimmer may be not provided with the operationmember. That is, the grass trimmer does not include one or both of thefirst operation member and the second operation member. The grasstrimmer is controlled by adopting a non-contact switch.

In one example, the grass trimmer is not provided with the secondoperation member and the second switch. The grass trimmer includes thenon-contact switch. In other words, the second switch is a non-contactswitch. The non-contact switch is configured to activate the motor 10 todrive at least one of the spool 53 and the housing 52 so that the spool53 and the housing 52 are relatively rotated to automatically wind thecutting line 101 to the spool 53.

In one example, the non-contact switch is a voice-activated switch. Inone example, the non-contact switch is a light-activated switch. In oneexample, the non-contact switch is an infrared sensor switch. In oneexample, the non-contact switch is magnetic switch. In one example, thenon-contact switch is a proximity switch.

The grass trimmer 100 further includes a remote controller. The remotecontroller is configured for the remote control to control the on/off ofthe non-contact switch. The user may adopt a mobile device, such as amobile phone, to control the grass trimmer 100.

In one example, the grass trimming head 50 and the non-contact switchare located on the same end of the connecting pipe 40.

In one example, the grass trimming head 50 and the non-contact switchare located on the two ends of the connecting pipe 40.

In one example, the non-contact switch is located inside the firsthousing 60.

In one example, the non-contact switch and the first switch 22 arelocated inside the handle housing 211.

In one example, the non-contact switch is located inside the connectingpipe 40.

As shown in FIG. 1 and FIG. 11A, the connecting pipe 40 includes aninner layer member 44 made of a fiber material and an outer layer member45 made of a fiber material. The outer layer member 45 is wrapped aroundan outer periphery of the inner layer member 44. A thickness of theinner layer member 44 is greater than a thickness of the outer layermember 45.

In one example, a fiber arrangement direction of the inner layer member44 is different from a fiber arrangement direction of the outer layermember 45.

The inner layer member 44 is rolled from multi-layered fiber materialsheets arranged layer by layer. The fiber arrangement direction of theinner layer member 44 extends along a straight line. The fiberarrangement direction of the inner layer member 44 coincides with anextending direction of the connecting pipe 40. Fibers of the outer layermember 45 are arranged in cross.

The inner layer member 44 has a relatively high strength. The outerlayer member 45 enhances the stability of combining the multi-layeredfiber material sheets. The connecting pipe 40 has a relatively highstrength, reliability and stability.

A wall thickness of the connecting pipe 40 is greater than or equal to0.5 mm, less than or equal to 1.5 mm.

In one example, a density of the motor housing 332 is greater than adensity of the handle housing 211. The density of the handle housing 211is greater than a density of the inner layer member 44.

In one example, the inner layer member 44 is made of a carbon fibermaterial. The outer layer member 45 is made of a carbon fiber material.The handle housing 211 is made of a plastic material. The motor housing332 is made of a metal material.

The connecting pipe 40 may be formed as a complete long pipe, or beformed by connecting a plurality of long pipes. In one example, theconnecting pipe 40 is formed by connecting the first connecting pipe 41and the second connecting pipe 42. The first connecting pipe 41 and thesecond connecting pipe 42 are connected by a connecting seat 43 tofacilitate the storage and transportation.

As shown in FIG. 3, the grass trimmer 100 further includes a fixingclamp 48. The fixing clamp 48 is formed by bending a metal sheet. Thefixing clamp 48 is sleeved on an outer periphery of the connecting pipe40. The connecting pipe 40 is fixed to the first housing 60 by thefixing clamp 48. The first housing 60 includes a first housing 61 and asecond housing 62. The connecting pipe 40 is located between the firsthousing 61 and the second housing 62. The first housing 60 furtherincludes an arm support member 63 for supporting the user's arm. The armsupport member 63 is located on an upper portion of the first housing60.

A ratio of a circumference of the connecting pipe 40 to a size of thefixing clamp 48 in the extending direction of the connecting pipe 40 isgreater than or equal to 6, and less than or equal to 16.

In one example, as shown in FIG. 11B, the connecting pipe 40 furtherincludes an embedded member 46. The inner layer member 44 is sleeved onan outer periphery of the embedded member 46. A material of the embeddedmember 46 is different from a material of the inner layer member 44. Theembedded member 46 is made of plastic or a metal material.

In one example, the inner layer member is a tubular body formed by thefiber material being surrounded or stacked.

As shown in FIG. 6, the grass trimming head 50 is configured to mountand accommodate the cutting line 101. One portion of the cutting line101 is accommodated inside the grass trimming head 50, and anotherportion of the cutting line 101 protrudes out of the grass trimming head50 to cut the vegetation when the grass trimming head 50 is rotated. Themotor 10 drives the grass trimming head 50 to rotate about a centralaxis 102 so as to drive the cutting line 101 to rotate to cut thevegetation. In one example, the motor may be replaced by an internalcombustion engine.

As shown in FIG. 7 and FIG. 8, the grass trimming head 50 includes thespool 53 and the housing 52. The motor 10 includes a motor shaft 11. Themotor shaft 11 is connected to the spool 53 to drive the spool 53 torotate. The housing 52 includes an upper housing 521 and a lower housing522. The grass trimming head 50 further includes a fan 58. The fan 58 isprovided with a blade for generating airflow. The motor 10 is configuredto drive the fan 58 to rotate to generate the airflow.

The grass trimmer 100 includes a damping device 80. In one example, thedamping device 80 includes a one-way bearing 81. The one-way bearing 81is configured to enable the housing 52 being in a one-way rotationalconnection to the motor 10. In one example, the one-way bearing 81 isconfigured to allow the housing 52 to rotate in only one direction withrespect to the motor 10 or the motor housing 332. That is, the one-waybearing 81 prevents the housing 52 from rotating in another directionwith respect to the motor 10 or the motor housing 332.

As shown in FIG. 6 to FIG. 10, the grass trimmer 100 is provided with asupport member 59. The support member 59 is fixed to motor 10 andenables the motor shaft 11 to pass therethrough. The support member 59is formed with a boss portion 591 to support an inner ring of theone-way bearing 81. The inner ring of the one-way bearing 81 is sleevedon an outer periphery of the boss portion 591 and fixed to the supportmember 59.

The one-way bearing 81 is connected to the housing 52. In one example,the one-way bearing 81 is connected to the housing 52 through anintermediate piece. The intermediate piece is configured to be a fan 58.The one-way bearing 81 is arranged between the support member 59 and thefan 58 instead of being directly connected to the housing 52, so thatthe fan 58 is rotated in only one direction with respect to the supportmember 59. The fan 58 is in a non-rotational connection to the housing52, thus the housing 52 is rotated in only one direction with respect tothe support member 59. The fan 58 is in a synchronous rotation with thehousing 52, that is, the fan 58 and the housing 52 are non-rotatablewith respect to each other.

In one example, the upper housing 521 is formed with a first connectingtooth 5214. The fan 58 is formed with a second connecting tooth 581connected to the first connecting tooth 5214. The first connecting tooth5214 and the second connecting tooth 581 are matched to realize asynchronous rotation of the first connecting tooth 5214 and the secondconnecting tooth 581. And the first connecting tooth 5214 and the secondconnecting tooth 581 are matched with respect to each other to play arole of guiding, so that the housing 52 is slidable with respect to thefan 58 along the central axis 102, and the fan 58 is rotatable alongwith the housing 52 about the central axis 102.

In one example, the one-way bearing is fixed to the housing.

In one example, the housing is formed with the blade for generating theairflow, that is, no separate fan is provided, in other words, the fanand the housing is arranged to be a whole.

In the cutting mode, the motor shaft 11 is rotated to drive the spool 53to rotate, and the spool 53 drives the upper housing 521 to rotate. Inone example, the spool 53 is formed with a first engaging tooth 536. Theupper housing 521 is formed with a first matching tooth 5211. The firstengaging tooth 536 is matched with the first matching tooth 5211, sothat the spool 53 drives the upper housing 521 to rotate.

The upper housing 521 drives the fan 58 to rotate. Under the action ofthe one-way bearing 81, the fan 58 is rotatable with respect to themotor housing 332 along a first direction (referring to a directionshown by an arrow 106 in FIG. 4). At this time, the motor 10 is rotatedin a forward direction to drive the spool 53 and the housing 52 torotate along the first direction, realizing the motor 10 driving thegrass trimming head 50 to rotate along the first direction. The motor 10drives the spool 53 and the housing 52 to synchronously rotate.

When the cutting line 101 needs to be replenished by the user, thecutting line 101 may pass through an outer aperture 544 on one side toenter into a housing cavity 511, and pass through an inner aperture 5351to pass through a line guide passage 5352, and then pass out from thehousing 52 through an outer aperture 544 on another side. When thecutting line 101 needs to be wound to the spool, the user does not needto open the housing, namely, disassembly the upper housing and the lowerhousing. The cutting line may be directly inserted into the housing, andthen be wound to be spool through the relative rotation of the spool andthe housing. Such grass trimming head is usually referred to as anexternally inserted winding grass trimming head.

The grass trimmer 100 is controlled by the user to execute theauto-winding mode. The motor 10 is reversely rotated to drive the spool53 to rotate along a second direction opposite to the first direction.Since the non-rotational effect of the one-way bearing 81, the fan 58cannot be rotated along the second direction. The fan 58 is connected tothe housing 52 through the first connecting tooth 5214 and the secondconnecting tooth 581, that is, the housing 52 is non-rotatable along thesecond direction. The spool 53 is, driven by the motor shaft 11, rotatedwith respect to the housing 52 along the second direction to realize theautomatic winding.

The first matching tooth 5211 or a second matching tooth 5223 is aratchet, so that the spool 53 and the housing 52 is rotatable withrespect to each other in the auto-winding mode, and the spool 53 candrive the housing 52 to rotate in the cutting mode.

The grass trimmer 100 further includes a fan cover 334 fixed to themotor housing 332. The fan cover 334 covers the blade of the fan 58 atleast in a radial direction of the central axis 102 to prevent the grassclippings from being wound around the fan 58. And the fan cover 334 isconfigured to change an airflow flowing direction of the fan 58, so thatthe airflow generated by the fan 58 blows the grass clippings outwardsand downwards along the radial direction of the central axis 102.

The motor shaft 11 directly drives the spool 53 to rotate. The housing52 is rotatable with respect to the spool 53, and is slidable withrespect to the spool 53 along the central axis 102. The housing 52 isslidable with respect to the spool 53 between a first axial position anda second axial position.

When the housing 52 is in the first axial position with respect to thespool 53, the first matching tooth 5211 is matched with the firstengaging tooth 536, so that the spool 53 drives the motor 52 tosynchronously rotate when the spool 53 is rotated.

The grass trimmer 100 has a feeding mode. The feeding mode is configuredto enable a portion of the cutting line 101 being wound around the spool53 to be released to increase a length of the cutting line 101 passingout from the grass trimming head 50. When the grass trimmer 100 is inthe cutting mode, the user knocks the grass trimming head 50, so thatthe housing 52 is moved to the second axial position from the firstaxial position, and the spool 53 is rotatable with respect to thehousing 52 to release a portion of the cutting line 101.

In one example, the spool 53 is formed with the first engaging tooth 536and a second engaging tooth 537. The housing 52 is formed with the firstmatching tooth 5211 matched with the first engaging tooth 536 and thesecond matching tooth 5223 matched with the second engaging tooth 537. Aplurality of first matching teeth 5211 are arranged along acircumferential direction of the central axis 102. A plurality of firstengaging teeth 536 are arranged along the circumferential direction ofthe central axis 102. In one example, the engaging tooth 536 is arrangedon an upper portion of the spool 53, and the second engaging tooth 537is arranged on a lower portion of the spool 53. The first matching tooth5211 is formed on the upper housing 521, and the second matching tooth5223 is formed on the lower housing 522.

When the housing 52 is moved to the second axial position, the firstmatching tooth 5211 is unengaged with the first engaging tooth 536, sothat the spool 53 and the housing 52 is rotatable with respect to eachother. At this time, the second engaging tooth 537 and the secondmatching tooth 5223 are matched so that the housing 52 is rotated by aspecific angle with respect to the spool 53 so as to release a specificlength of cutting line 101.

The grass trimming head 50 further includes a spring 57. The spring 57is configured to apply an acting force between the upper housing 522 andthe spool 53 so that the housing 52 is moved to the first axial positionin which the housing 52 is synchronously rotated with the spool 53. Inone example, the spring 57 is a compression spring. When the housing 52is not subject to an external force generated by the user knocking theground, the spring 57 applies the acting force to the housing 52 to makethe housing 52 back to the first axial position. The spool 53 is formedwith a groove 5344. The spring 57 is arranged inside the groove 5344.The lower housing 522 is provided with a protrusion portion 5221protruding towards the upper housing 521. The protrusion portion 5221and the groove 5344 are matched to guide the housing 52 to move withrespect to the spool 53 between the first axial position and the secondaxial position. The spring 57 is arranged between the protrusion portion5221 and the spool 53. One end of the spring 57 is in contact with theprotrusion portion 5221, and another end of the spring 57 is providedwith a first contact member 571. The first contact member 571 reduceswear between the spool 53 and the spring 57.

The first contact member 571 is a metal member. The spool 53 and thehousing 52 are plastic members.

In one example, the spring may not be in direct contact with thehousing. In one example, the contact member is arranged between thespring and the housing. The contact member is in direct contact with thespring.

In one example, the first engaging tooth is arranged on the lowerportion of the spool, the first matching tooth is formed on the lowerhousing. The spring applies the acting force to the spool or the housingassembly so that the first matching tooth and the first engaging toothare in contact.

The spool 53 is provided with the inner aperture 5351 for the cuttingline 101 to be inserted into, and the inner aperture 5351 is capable offixing the cutting line 101.

The grass trimming head 50 includes a housing assembly 51. The housingassembly 51 is formed with the housing cavity 511 and the outer aperture544. The cutting line 101 may be inserted into the housing cavity 511from the outside of the housing assembly 51. At least a portion of thespool 53 is arranged inside the housing cavity 511. The spool 53 isrotatable with respect to the housing assembly 51 about the central axis102.

In one example, the housing assembly 51 includes the housing 52 and aneyelet member 54. The housing 52 is formed with the housing cavity 511.The eyelet member 54 is formed with an outer aperture 544. The eyeletmember 54 is fixed to the housing 52. The eyelet member 54 is made of ametal material. The housing 52 is made of a plastic material. The eyeletmember 54 may prevent the cutting line 101 form wearing a hole wall ofthe outer aperture 544.

In one example, the housing assembly includes the housing, and thehousing assembly does not include the eyelet member. The housing isformed with the outer aperture. In one example, the housing includes theupper housing and the lower housing, in other words, the housingassembly includes the upper housing and the lower housing.

The inner aperture 5351 and the outer aperture 544 may be automaticallyaligned, so that it is convenient for the user to insert the cuttingline 101 into the housing cavity 511 through the outer aperture 544 andinsert the cutting line 101 into the inner aperture 5351. In otherwords, the cutting line 101 passing through the outer aperture 544 maybe directly inserted into the inner aperture 5351.

The housing assembly 51 is formed with a first positioning surface 5212.The spool 53 is formed with a second positioning surface 5362 matchedwith the first positioning surface 5212. When the first positioningsurface 5212 is in contact with the second positioning surface 5362, theinner aperture 5351 is aligned with the outer aperture 544.

The grass trimming head 50 further includes a driving member. Thedriving member is configured to apply an acting force to the housingassembly 51 or the spool 53, and the acting force causes the housingassembly 51 and the spool 53 to rotate with respect to each other sothat the first positioning surface 5212 and the second positioningsurface 5362 are in contact.

In one example, the spring 57 is the driving member. The spring 57 isarranged between the housing assembly 51 and the spool 53. The spring 57applies an acting force to the spool 53 or the housing assembly 51, andthe acting force causes the first positioning surface 5212 and thesecond positioning surface 5362 to go towards each other.

The first matching tooth 5211 or the first engaging tooth 536 has aninclined surface inclined to a normal surface of the central axis 102.An angle between the inclined surface and the normal surface of thecentral axis 102 is greater than or equal to 8 degrees, and less than orequal to 18 degrees. By arranging the inclined surface, the firstmatching tooth 5211 and the second matching tooth 5223 enables the spool53 and the housing 52 to relatively rotate under the driving by theacting force of the spring 57.

As shown in FIG. 21A and FIG. 21B, in one example, the first matchingtooth 5211 is formed with a first inclined surface 5213 and the firstpositioning surface 5212. The first engaging tooth 536 is formed with asecond inclined surface 5361 and the second positioning surface 5362.

The first inclined surface 5213 and the first positioning surface 5212are located on two sides of the first matching tooth 5211. The secondinclined surface 5361 and the second positioning surface 5362 arelocated on two sides of the first engaging tooth 536.

When the first positioning surface 5212 is in contact with the secondpositioning surface 5362, the two sides of the first matching tooth 5211are in contact with two adjacent first engaging teeth 536 respectively.

When the first positioning surface 5212 is in contact with the secondpositioning surface 5362, the first inclined surface 5213 is in contactwith the second inclined surface 5361.

The spool 53 is formed with a plurality of inner apertures 5351. An evennumber of the inner apertures 5351 are provided. An even number of firstengaging teeth 536 are provided. The plurality of inner apertures 5351are evenly distributed in a circumferential direction of an axis of thespool 53. In one example, a number of the first engaging teeth 536 isthe same as a number of the inner apertures 5351.

In one example, a number of the second engaging teeth 537 is the same asa number of the inner apertures 5351. For example, the spool 53 isformed with six inner apertures 5351, and the spool 53 is formed withsix first engaging teeth 536 and six second engaging teeth 537.

The spool 53 is formed with at least one winding portion 531 for thecutting line 101 winding and two flange portions 532 arranged on twoends of the winding portion 531. The inner aperture 5351 is arranged onthe two flange portions 532.

In one example, the spool 53 includes two winding portions 531 and threeflange portions 532.

The spool 53 includes an upper winding portion 5331, a lower windingportion 5341, a middle flange portion 535, an upper flange portion and alower flange portion. The upper winding portion 5331 is configured forwinding the cutting line 101 and the lower winding portion 5341 isconfigured for winding the cutting line 101. The upper flange portion,the lower flange portion and the middle flange portion 535 areconfigured to limit a position of the cutting line 101. The upper flangeportion is connected to an upper end of the upper winding portion 5331.The lower flange portion is connected to a lower end of the lowerwinding portion 5341. The middle flange portion 535 is located betweenthe upper winding portion 5331 and the lower winding portion 5341. Inone example, the middle flange portion 535 is formed with the inneraperture 5351 for the cutting line 101 to be inserted into.

The spool 53 includes a first part and a second part. The first part andthe second part are referred to as an upper spool 533 and a lower spool534 respectively. The lower spool 534 is coupled to the upper spool 533to form a whole. The upper spool 533 includes the upper winding portion5331, a first flange portion 5332 and a second flange portion 5333. Thelower spool 534 includes the lower winding portion 5341, a third flangeportion 5342 and a fourth flange portion 5343. The first flange portion5332 is connected to the upper end of the upper winding portion 5331.The second flange portion 5333 is connected to a lower end of the upperwinding portion 5331. The third flange portion 5342 is connected to anupper end of the lower winding portion 5341. The fourth flange portion5343 is connected to the lower end of the lower winding portion 5341.The first flange portion 5332 is the upper flange portion, and thefourth flange portion 5343 is the lower flange portion. The secondflange portion 5333 and the third flange portion 5343 cooperatively formthe middle flange portion 535.

The upper spool 533 is coupled to the lower spool 534 to form the lineguide passage 5352 for cutting line 101 passing through the spool 53.Two ends of the line guide passage 5352 are defined as the innerapertures 5351. The cutting line 101 may be inserted into the line guidepassage 5352 through the inner aperture 5351.

The line guide passage 5352 extends along a curve.

The upper spool 533 is coupled to the lower spool 534 to form two lineguide passages 5352 intersected with each other. In one example, theupper spool 533 is coupled to the lower spool 534 to form three lineguide passages, any two of which are intersected with each other. Thethree line guide passages 5352 is arranged around the central axis 102.

The line guide passage 5352 is formed by the upper spool 533 and thelower spool 534, which is beneficial for the processing andmanufacturing of the line guide passage 5352.

The spool 53 is arranged between the upper housing 521 and the lowerhousing 522. The spool 53 is formed with the groove 5344. In oneexample, the lower spool 534 is formed with the groove 5344. The lowerhousing 522 is provided with the protrusion portion 5221 protrudingtowards the upper housing 521. The protrusion portion 5221 and thegroove 5344 are matched to guide the housing 52 to move with respect tothe spool 53 along the central axis 102. At least a portion of thespring 57 is located inside the groove 5344. The spring 57 is arrangedthroughout the groove 5344 and between the upper spool 533 and the lowerhousing 522. The spring 57 applies an acting force so that the upperspool 533 and the lower housing 522 are moved away from each other. Inother words, the spring 57 applies an acting force so that the upperhousing 521 and the upper spool 533 are moved closer to each other.

The upper spool 533 is fixed to the motor shaft 11. The motor 10 drivesthe upper spool 533 to rotate.

The housing assembly 51 is provided with the protrusion portion 5221protruding towards the housing cavity 511. A minimum distance from theprotrusion portion 5221 to the inner aperture 5351 is greater than orequal to 3 mm.

The hole wall of the outer aperture 544 protrudes towards the housingcavity 511 to form the protrusion portion 5221. In one example, theouter aperture 544 is provided with two protrusion portions 5221. Thetwo protrusion portions 5221 are located on two sides of the outeraperture 544 and arranged along the circumferential direction of thecentral axis 102. That is, the two protrusion portions 5221 are locatedon left and right sides of the outer aperture 544 instead of upper andlower sides.

In one example, the eyelet member 54 is formed with the outer aperture544. A distance from the eyelet member 54 to the spool 53 is less than 3mm. A distance from the eyelet member 54 to the flange portion 532 isless than or equal to 3 mm. In one example, a distance from the eyeletmember 54 to the middle flange portion 535 is less than or equal to 3mm.

A end portion of the cutting line 101 being inserted into the housingcavity 511 through the outer aperture 544 is less likely to be deviated,and can be smoothly inserted into the inner aperture 5351.

At least portion of the eyelet member 54 protrudes towards the spool 53.The eyelet member 54 is formed with two bumps 542 protruding towards thespool 53. The two bumps 542 are arranged on two sides of an observationhole, and arranged along the circumferential direction of the centralaxis 102.

The two bumps 542 are located between an upper surface and a lowersurface of the middle flange portion 535. A size of each bump 542 alonga direction of the central axis 102 is less than a size of the middleflange portion 535 along the direction of the central axis 102.

The outer aperture 544 is a waist-shaped hole. A size of the outeraperture 544 along the direction of the central axis 102 is defined as aheight of the outer aperture 544. A size of the outer aperture 544 alonga direction perpendicular to the central axis 102 is defined as a widthof the outer aperture 544. A size of the outer aperture 544 in anextending direction is defined as a depth of the outer aperture 544.

A distance between the two bumps 542 is the same as the width of theouter aperture 544. The width of the outer aperture 544 is greater thanthe height of the outer aperture 544.

The eyelet member 54 is formed with a notch 543 on one side of aprojection of the eyelet member 54 on a plane perpendicular to thecentral axis 102 facing towards the spool 53. The eyelet member 54 isU-shaped.

The eyelet member 54 includes a body 541 and the two bumps 542. The body541 is formed with the outer aperture 544. The two bumps 542 extendoutward from the body 541. The two bumps 542 extend outward from a sameside of the body 541.

The distance from the eyelet member 54 to the flange portion 532 is lessthan a maximum outer diameter of the cutting line 101.

As shown in FIG. 6, FIG. 7 and FIG. 12, the grass trimming head 50further includes a knocking cap 55. The knocking cap 55 is rotatablyconnected to the lower housing 522 so that the knocking cap 55 and thelower housing 522 are rotatable with respect to each other. At the sametime, the knocking cap 55 is synchronously moved with the lower housing522 in a direction of the axis. In other words, when a position of theknocking cap 55 is changed, the lower housing 522 is moved along withthe knocking cap 55, namely, the housing 52 will change the axialposition by knocking the knocking cap 55.

The knocking cap 55 includes a contact portion 551 protruding out of anouter surface of the housing 52.

A ratio of a projection area of the contact portion 551 on the planeperpendicular to the central axis 102 to a projection area of thehousing 52 on the plane perpendicular to the central axis 102 is greaterthan or equal to 0.3, and less than or equal to 1.

A surface of the contact portion 551 is a smooth curved surface. Aprojection of the contact portion 551 on the plane perpendicular to thecentral axis 102 has a circular shape.

A ratio of the projection area of the contact portion 551 on the planeperpendicular to the central axis 102 to a projection area of the spool53 on the plane perpendicular to the central axis 102 is greater than orequal to 0.5, and less than or equal to 1.2.

A ratio of a maximum size of the contact portion 55 in the radialdirection of the central axis 102 to a maximum size of the spool 53 inthe radial direction of the central axis 102 is greater than or equal to0.7, and less than or equal to 1.1.

An area of the contact portion 551 is relatively large, so that grasstrimming head 50 is ensured to be in contact with the ground before thehousing 52 is in contact with the ground when the grass trimming head 50is obliquely knocked by the user, which effectively avoids the wear ofthe housing 52.

A bearing 56 is arranged between the knocking cap 55 and the lowerhousing 522, and connected to the knocking cap 55 and the lower 522. Thelower housing 522 is formed with a mounting groove 5222. In one example,the protrusion portion 5221 is formed with the mounting groove 5222. Thebearing 56 is arranged inside the mounting groove 5222. The bearing 56is connected to the knocking cap 55 and the lower housing 522.

Under the action of the bearing 56, the knocking cap 55 is freelyrotatable with respect to the lower housing 522, reducing the wear ofthe grass trimming head 50. The spring 57 applies the acting force tothe housing 52 so that the housing 52 is moved downward with respect tothe spool 53. A shock absorbing member for slowing the impact betweenthe lower housing 521 and the spool 53 is arranged between the lowerhousing 521 and the spool 53. In one example, the shock absorbing memberis a rubber gasket.

As shown in FIG. 22 and FIG. 23, a grass trimming head 201 includes aspool 203 and a housing assembly. The housing assembly is formed with ahousing cavity and an outer aperture. The cutting line can be insertedinto the housing cavity from the outside of the housing assembly. Atleast a portion of the spool 203 is arranged inside the housing cavity.The spool 203 is rotatable with respect to the housing assembly aboutthe central axis.

In one example, the housing assembly includes a housing 202 and aneyelet member 204. The housing 202 is formed with the housing cavity.The eyelet member 204 is formed with the outer aperture, and fixed tothe housing 202. The housing 202 includes an upper housing 202 a and alower housing 202 b.

A structure of the housing 202 in FIG. 22 is the same as a structure ofthe housing 52 in FIG. 1 to FIG. 12. The differences between the grasstrimming head 201 in FIG. 22 and the grass trimming head 50 in FIG. 1 toFIG. 12 are that the spool 203 and the eyelet member 204 are differentfrom the spool 53 and the eyelet member 54 in FIG. 1 to FIG. 12.

In one example, the spool 203 is formed with a bump 203 a towards thehousing 202. The eyelet member 204 is not provided with a bump. In oneexample, the spool 203 includes a winding portion 203 b and a flangeportion 203 c. An inner aperture 203 d is arranged on the flange portion203 c. The bump 203 a is arranged on the flange portion 203 c. Two bumps203 a are provided and located on two sides of the inner aperture 203 d.The two bumps are arranged to guide the end portion of the cutting lineentering the housing cavity, which is beneficial for the cutting linebeing directly inserted into the inner aperture 203 d.

A minimum distance from the bump 203 a to the outer aperture is lessthan or equal to 3 mm. A minimum distance from the bump 203 a to theeyelet member 204 is less than or equal to 3 mm. The minimum distancefrom the bump 203 a to the outer aperture is less than or equal to amaximum outer diameter of the cutting line. The maximum outer diameterof the cutting line is a maximum size of a cross section of the cuttingline perpendicular to an extending direction of the cutting line.

In one example, a difference between a grass trimming head in FIG. 24and the grass trimming head 50 in FIG. 1 to FIG. 12 is that a bump 303is formed by a housing 302 instead of the eyelet member. A spool 301 andthe spool 53 are the same in structure.

As shown in FIG. 25 and FIG. 26, a spool 401 includes two windingportions and three flange portions. In one example, the spool 401includes an upper winding portion, a lower winding portion, a middleflange portion, an upper flange portion and a lower flange portion. Theupper winding portion and the lower winding portion are configured forthe cutting line winding around. The upper flange portion, the lowerflange portion, and the middle flange portion are configured to limit aposition of the cutting line. The upper flange portion is connected toan upper end of the upper winding portion. The lower flange portion isconnected to a lower end of the lower winding portion. The middle flangeportion is located between the upper winding portion and the lowerwinding portion. In one example, the middle flange portion is formedwith an inner aperture for the cutting line to be inserted into. A wholestructure of the spool 401 shown in FIG. 25 and FIG. 26 is the same asthe whole structure of the spool 53 shown in FIG. 1 to FIG. 12, and adifferent therebetween is that structures of the pieces combined intothe spool 401 are different.

In one example, the spool 401 includes a first piece 403 and a secondpiece 402. The first piece 403 and the second piece 402 are combinedinto the spool 401. The first piece 403 is formed with a winding portionand a flange portion. In one example, the first piece 403 is formed withan upper winding portion, a lower winding portion, a middle flangeportion, an upper flange portion and a lower flange portion.

The spool 401 is formed with at least two line guide passages 404intersected with each other. In one example, the spool 401 is formedwith three line guide passages 404. The first piece 403 and the secondpiece 402 are combined to form the line guide passages 404. Two ends ofthe line guide passages 404 are defined as inner apertures. In oneexample, an intersection portion of the two line guide passages 404intersected with each other is formed by the combination of the firstpiece 403 and the second piece 402. The first piece 403 is arrangedaround the second piece 402, and arranged on an outer periphery of thesecond piece 402.

The spool 401 is constructed in a manner that the spool can beconstructed and machine shaped by a simple mold, which is simple andquick in manufacture.

As shown in FIG. 27 to FIG. 29, a spool 501 is formed with at least onewinding portion 504 for the cutting line winding around and two flangeportions 505 a and 505 b arranged on two ends of the winding portion504. An inner aperture 507 is arranged on the flange portions 505 a and505 b.

In one example, the spool 501 is formed with one winding portion 504. Anupper flange portion 505 a and a lower flange portion 505 b are locatedon the two ends of the winding portion 504 respectively. The inneraperture 507 is arranged on the upper flange portion 505 a and the lowerflange portion 505 b.

The spool 501 includes a first piece 502 and a second piece 503. Thefirst piece 502 and the second piece 503 are combined to form the spool501. The first piece 502 is formed with a winding portion 504. The firstpiece 502 and the second piece 503 together form an upper flange portion505 a and a lower flange portion 505 b. The first piece 502 and thesecond piece 503 are arranged along a rotational axis of the spool 501.The second piece 503 is located above the first piece 502.

The first piece 502 and the second piece 503 are formed with the lineguide passage 506. In one example, the first piece 502 and the secondpiece 503 are combined to form at least two line guide passages 506intersected with each other. In one example, the first piece 502 and thesecond piece 503 are combined to form three line guide passages 506, anytwo of which are intersected with each other. Two ends of the line guidepassages 506 are defined as inner apertures 507.

As shown in FIG. 30 to FIG. 32, a grass trimming head 601 includes aspool 603 and a housing assembly. The housing assembly is formed with ahousing cavity and provided with an outer aperture for cutting linepassing through the housing cavity from the outside of the housingassembly. The housing assembly includes a housing 602 and an eyeletmember 604. The housing 602 is formed with a housing cavity. At least aportion of the spool 603 is located inside the housing cavity. Thehousing 602 includes an upper housing 602 a and the lower housing 602 b.The eyelet member 604 is formed with an outer aperture. A spring 605 isarranged between the lower housing 602 b and the spool 603.

Structures of the spool 603 and the housing assembly in FIG. 30 to FIG.32 are the same as the structures of the spool 53 and the housingassembly in FIG. 1 to FIG. 12. A difference between the grass trimminghead 601 in FIG. 30 to FIG. 32 and the grass trimming head 50 in FIG. 1to FIG. 12 is that the grass trimming head 601 further includes anelastic member 603 a. The elastic member 603 a is a driving member. Inone example, the elastic member 603 a is an elastic tab. The elasticmember 603 a is fixed to a bottom portion of the spool 603, andconnected to the spool 603 and the housing assembly. One end of theelastic member 603 a is in contact with the lower housing 602 b. Theelastic member 603 a applies an acting force to the lower housing 602 b,and the acting force causes the lower housing 602 b to rotate withrespect to the spool 603 so that a first positioning surface and asecond positioning surface go towards each other. In on example, whenthe elastic member 603 a is compressed, the elastic member 603 generatesat least one component force causing the lower housing 602 b to rotatewith respect to the spool 603, thereby driving the housing assembly torotate with respect to the spool 603. When the first positioning surfaceis in contact with the second positioning surface, the spool 603prevents the housing assembly from rotating. The elastic member 603drives the housing 602 to rotate with respect to the spool 603, and theouter aperture is aligned with the inner aperture when the firstpositioning surface is in contact with the second positioning surface.The automatic alignment of the outer aperture and the inner aperture isconvenient for the user. The user can conveniently insert the cuttingline into the inner aperture through the outer aperture.

In one example, a torsion spring may be used as the driving member. Thetorsion spring is in contact with the spool and the housing to apply anacting force to the housing, and the acting force causes the housing torotate with respect to the spool.

In one example, the driving member drives the spool to rotate withrespect to the housing assembly. The driving member applies an actingforce to the spool, and the acting force causes the spool to rotate withrespect to the housing assembly.

In one example, the driving member drives the spool and the housingassembly to rotate. The driving member applies an acting force to thespool and the housing assembly, and the acting force causes the firstpositioning surface and the second positioning surface to go towardseach other.

As shown in FIG. 33 to FIG. 36, a grass trimming head 701 includes ahousing assembly. The housing assembly is formed with a housing cavityand an outer aperture. The cutting line can be inserted into the housingcavity from the outside of the housing assembly. At least a portion of aspool 704 is arranged inside the housing cavity. The spool 704 isrotatable with respect to the housing assembly about a central axis. Thespool 704 is provided with an inner aperture for the cutting line to beinserted into. The inner aperture is configured to fix the cutting line.

In one example, the housing assembly includes a housing 703 and aneyelet member 705. The housing 703 is formed with the housing cavity.The housing 703 includes an upper housing 703 a and a lower housing 703b. The eyelet member 705 is formed with an outer aperture, and fixed tothe housing 703. The housing assembly is formed with a first positioningsurface. The spool 704 is formed with a second positioning surfacematched with the first positioning surface. When the first positioningsurface is in contact with the second positioning surface, the inneraperture is aligned with an outer aperture.

The grass trimming head 701 further includes a fan 703. The fan 703 issynchronously rotated with the housing 703. The fan 702 in FIG. 33 toFIG. 36 is the same as the fan 58 in FIG. 1 to FIG. 12.

The grass trimming head 701 further includes a magnetic member. Themagnetic member is used as the driving member. The magnetic memberapplies an acting force to the housing assembly or the spool 704, andthe acting force causes the first positioning surface and the secondpositioning surface to go towards each other. The magnetic memberapplies an acting force to the housing assembly or the spool 704, andthe acting force causes the housing assembly and the spool 704 to rotatewith respect to each other so that the first positioning surface is incontact with the second positioning surface.

In one example, a first magnetic member 707 is fixed to the housing 703,and a second magnetic member 708 is fixed to the spool 704. A magneticdirection of the second magnetic member 708 is opposite to a magneticdirection of the first magnetic member 707. The first magnetic member707 and the second magnetic member 708 repel each other to generate anacting force causing the spool 704 and the housing 703 to rotate withrespect to each other.

In one example, the housing 703 is formed with a first matching tooth703 c. One end of the first matching tooth 703 c is provided with afirst positioning surface. The first magnetic member 707 is fixed to oneend of the first matching tooth 703 c facing away from the firstpositioning surface.

The spool 704 is formed with a first engaging tooth 704 a. One end ofthe first engaging tooth 704 a is provided with a second positioningsurface. The second magnetic member 708 is fixed to one end of the firstengaging tooth 704 a facing away from the second positioning surface. Astructure of the first matching tooth 703 c of the housing assembly inFIG. 33 to FIG. 36 is different from the structure the first matchingtooth 5211 of the housing assembly 51 in FIG. 1 to FIG. 12, while otherstructures thereof are the same. A structure of the first engaging tooth704 a of the spool 704 in FIG. 33 to FIG. 36 is different from thestructure of the first engaging tooth 536 of the spool 53 in FIG. 1 toFIG. 12, while other structures thereof are the same. The firstpositioning surface in FIG. 33 to FIG. 36 is the same as the firstpositioning surface 5212 in FIG. 1 to FIG. 12. The second positioningsurface in FIG. 33 to FIG. 36 is the same as the second positioningsurface 5362 in FIG. 1 to FIG. 12.

In one example, a number of first engaging teeth 704 a is the same as anumber of inner apertures. A number of first magnetic members 707 is thesame as a number of the inner apertures. A number of second magneticmembers 708 is the same as a number of the inner apertures. In oneexample, six inner apertures are provided.

In one example, the grass trimmer includes a magnetic member and a metalmember. The magnetic member is fixed to one of the spool and thehousing, and the metal member is fixed to another of the spool and thehousing. The magnetic member generates a suction force to the metalmember. The magnetic member drives the housing assembly or the spool 704to rotate with respect to the other one so that the first positioningsurface is in contact with the second positioning surface, realizing theautomatic alignment of the inner aperture and the outer aperture.

As shown in FIG. 37 and FIG. 38, a grass trimming head 801 includes ahousing 802, a spool 803, a knocking cap 807, a knocking cap supportingmember 806 and a spring 805. The spool 803 is configured for the cuttingline wining. At least portion of the spool 803 is arranged inside thehousing 802, and the spool 803 is rotatable with respect to the housing803 about a central axis. The housing 802 includes an upper housing 802a and a lower housing 802 b. The spool 803 is located between the upperhousing 802 and the lower housing 802 b. The upper housing 802 a isformed with a first matching tooth. The knocking cap supporting member806 is formed with a first engaging tooth matched with the firstmatching tooth. In one example, the first engaging tooth is arranged onan inner surface of the knocking cap supporting member 806. An eyeletmember 804 is fixed to the housing 802. The eyelet member 804 is formedwith an outer aperture.

The spring 805 is arranged between the knocking cap supporting member806 and the upper housing 802 a. The knocking cap 807 is rotatablyconnected to the knocking cap supporting member 806. The knocking cap807 includes a contact portion 807 a protruding out of an outer surfaceof the housing 802. The contact portion 807 a is configured to be incontact with the ground. The lower housing 802 b is formed with anoutlet. The knocking cap 807 protrudes out of the housing 802 from theoutlet. The spool 803 is formed with a guiding portion. The knocking capsupporting member 806 is formed with a cooperating portion. Thecooperating portion is arranged on an outer surface of the knocking capsupporting member 806. The guiding portion and the cooperating portionare matched so that the spool 803 and the knocking cap supporting member806 remain in a synchronous rotation and are slidable along the centralaxis.

A ratio of a projection area of the contact portion 807 a on a planeperpendicular to the central axis to a projection area of the housing802 on the plane perpendicular to the central axis is greater than orequal to 0.3, and less than or equal to 1. A surface of the contactportion 807 a is a smooth curved surface. A projection of the contactportion 807 a on the plane perpendicular to the central axis has acircular shape.

In on example, the knocking cap supporting member and the spool may be awhole, that is, the knocking cap is rotatably connected to the spool.

As shown in FIG. 39 and FIG. 40, a grass trimming head 210 is configuredto mount and accommodate a cutting line. One portion of the cutting lineis accommodated inside the grass trimming head 210, and another portionof the cutting line protrudes out of the grass trimming head 210 to cutthe vegetation when the grass trimming head 210 is rotated.

The motor 220 is configured to drive the grass trimming head 210 torotate about a central axis 210 a, thereby driving the cutting line torotate to cut the vegetation. In one example, the motor 220 includes amotor shaft 220 a. The motor shaft 220 a is connected to the grasstrimming head 210 to drive the grass trimming head 210 to rotate.

The grass trimming head 210 includes a spool 260 and a housing 250. Thespool 260 is configured for the cutting line winding around andaccommodated inside the housing 250. The spool 260 is provided with aninner aperture 260 a. The inner aperture 260 a is configured for fixingthe cutting line or for the cutting line passing through. The housing250 is formed with an outer aperture 250 a for the cutting line passingthrough. In one example, the housing 250 includes an upper housing 250 band a lower housing 250 c, which is convenient for the housing 250 to beassembled with the spool 260 and for the user to open the housing 250 todetect a situation inside the housing 250.

The grass trimming head 210 further includes a spring 270 applying anacting force between the housing 250 and the spool 260. The spring 27applies an acting force causing the spool 260 to go away from the lowerhousing 250 c.

When the cutting line needs to be replenished by the user, the user mayalign the inner aperture 260 a with the outer aperture 250 a, and theninsert the cutting line into the inner aperture 260 a through the outeraperture 250 a. As long as the spool 260 and the housing 250 are movedwith respect to each other, the cutting line is limited by the outeraperture 250 a so that the cutting line is gradually wound around thespool 260 with the moving of the outer aperture 250 a with respect tothe spool 260. The motor shaft 220 a is connected to the spool 260, anddirectly drives the spool 260 to rotate about the central axis 210 a.The spool 260 is rotatably connected to the housing 250.

The grass trimmer further includes a damping device 240. In one example,the damping device 240 includes a friction member 230. The frictionmember 230 is movable along a direction 230 a. When the friction member230 is moved to be in contact with the housing 250, the friction member230 causes, due to the contact friction, the housing 250 to have atendency to rotate about the spool 260. With the increase of thefriction force, the friction member 230 causes the spool 260 and thehousing 250 to rotate with respect to each other, so that the grasstrimmer has an auto-winding mode. The motor 220 drives at least one ofthe spool 260 and the housing 250 so that the spool 260 and the housing250 are rotated with respect to each so as to automatically wind thecutting line around the spool 260. In one example, under the driving ofthe motor 220 and the action of the friction member 230, the spool 260and the housing 250 are rotated with respect to each other so as toautomatically wind the cutting line around the spool 260. The frictionmember 230 does not completely prevent the housing 250 from rotating,but only reduce a rotational speed of the housing 250, thereby realizingthe relative rotation of the spool 260 and the housing 250.

Of course, when the spool 260 is wound by enough cutting line and aportion of the cutting line protruding out of the housing 250 is notsufficient to cut the vegetation, the spool 260 and the housing 250 isrelatively rotated to realize the automatic string release.

In one example, the friction member 230 is configured to generate adamping function on the housing 250 so as to slow down the rotation ofthe housing 250, thereby causing the housing 250 and the spool 260 torelatively rotate. The user may directly or indirectly operate thefriction member 230 to realize the cutting mode and the auto-windingmode of the grass trimmer. Of course, the user may firstly place thefriction member 230 under a state corresponding to a desired mode andthen start the motor 220.

As shown in FIG. 41 and FIG. 42, in one example, a grass trimming head310 includes a spool 350 and a housing 320. The housing 320 includes anupper housing 320 a and a lower housing 320 b.

Compared to the damping device 240 in FIG. 39 and FIG. 40, a dampingdevice 340 in FIG. 41 and FIG. 42 includes a stopping member 330 forpreventing the housing 320 from rotating. The housing 320 is formed witha stopping groove 320 c matched with the stopping member 330. In oneexample, the stopping groove 320 c is arranged on the upper housing 320a. In the auto-winding mode, the stopping member 330 is inserted intothe stopping groove 320 c and matched with the stopping groove 320 c, sothat the housing 320 is completely prevented from rotating with respectto the whole grass trimmer. Also, the relative rotation of the spool 350and the housing 320 is realized so that the cutting line can beautomatically wound around the spool 350, realizing the automaticwinding function.

The stopping member 330 is also configured to damp the rotation of thehousing 320. The difference is as follows. The damping effect of thefriction member 230 is to slow down the moving tendency. The dampingeffect of the stopping member 330 is to limit the displacement. Theslowing down of the moving tendency and the limitation of thedisplacement are both defined as damping. The friction member 230 andthe stopping member 330 may be both considered as the damping device340.

FIG. 43 shows a solution in which a motor shaft 460 a of the motor 460drives the housing 420 and a one-way bearing 440 is adopted to damp thespool 430.

As shown in FIG. 43, the grass trimming head 410 includes a spool 430and a housing 420. The motor 460 is accommodated by the motor housing450. The one-way bearing 440 is arranged between the spool 430 and themotor housing 450 so that the spool 430 is rotatable with respect to themotor housing 450 in only one direction. In one example, the motorhousing 450 is formed with a boss portion. An inner ring of the one-waybearing 440 is sleeved on an outer periphery of the boss portion, andfixedly connected to the motor housing 450. An outer ring of the one-waybearing 440 is rotatable with respect to the motor housing 450 in onlyone direction. The outer ring of the bearing 440 is prevented fromrotating with respect to the motor housing 450 in another direction. Thespool 430 is sleeved on the outer ring of the one-way bearing 440. Theone-way bearing 440 enables the spool 430 to rotate with respect to themotor housing 450 in only one direction.

The motor shaft 460 a is arranged throughout the spool 430 and does notdirectly drive the spool 430, namely the motor shaft 460 does notdirectly transmit the torque to the spool 430. The motor shaft 460 a isin a non-rotational connection to the housing 420 and directly drivesthe housing 420.

According to the foregoing solutions and principles, when the motor 460is rotated in a forward direction, the spool 430 and the housing 420 maybe synchronously rotated to perform the cutting mode. And when the motor460 is rotated in a reverse direction, the spool 430 remains still, andthe spool 430 and the housing 420 may be relatively rotated to performthe auto-winding mode.

It will be appreciated that the damping device may not only apply aresistance force damping the rotation of the housing to the housing, butalso apply a resistance force damping the rotation of the spool to thespool.

In one example, the damping device may apply the damping effect to thespool and the housing. In one example, the damping device may include afirst damping member and a second damping member. The first dampingmember applies a first resistance force damping the rotation of thespool to the spool. The second damping member applies a secondresistance force damping the rotation of the housing to the housing. Dueto the first resistance force and the second resistance force, thehousing and the spool are relatively rotatable.

As shown in FIG. 44 to FIG. 48, a grass trimmer 510 includes a grasstrimming head 520, a first motor 530, a second motor 540, a connectingpipe 550 and a handle 560.

The grass trimming head 520 is configured to mount or fix the cuttingline 510 a. The handle 560 is used for being gripped by the user. Thegrass trimmer 510 includes a trigger 560 a. The trigger 560 a isconfigured to activate the first motor 530 and the second motor 540. Thetrigger 560 a is arranged on the handle 560. When gripping the handle560, the user can operate the trigger 560 a to control the first motor530 and the second motor 540. The connecting pipe 550 is connected tothe handle 560 and the grass trimming head 520. The grass trimmer 510further includes an auxiliary handle 560 b. The auxiliary handle 560 bis fixed to the connecting pipe 550. In one example, the auxiliaryhandle 560 b is located between the grass trimming head 520 and thehandle 560. The user can grip the handle 560 and the auxiliary handle560 b by both hands respectively. In one example, the connecting pipe550 has a hollow tubular structure, and substantially extends along astraight line.

The grass trimmer 510 further includes a power supply device forsupplying power to the first motor 530 and the second motor 540. In oneexample, the power supply device is a battery pack 570. Of course, thepower supply device may be a cable or an interface that is connected toan AC power supply network or a battery. The cable or the interface maysupply the power of the AC power supply network or the battery to thegrass trimmer 510.

The grass trimmer 510 includes a main housing 580. The battery pack 570is fixed by the main housing 580. The battery pack 570 is detachablyconnected to the main housing 580. The main housing 580 is fixed to oneend of the connecting pipe 550. The grass trimmer 510 includes a circuitboard for controlling the first motor 530 and the second motor 540. Thecircuit board is arranged inside the main housing 580.

The grass trimmer 510 further includes a motor housing 590. The firstmotor 530 and the second motor 540 is accommodated by the motor housing590. The motor housing 590 is fixed to another end of the connectingpipe 550. The connecting pipe 550 is connected to the main housing 580and the motor housing 590. The motor housing 590 and the main housing580 are fixed to two ends of the connecting pipe 550 respectively.

The grass trimming head 520 includes a spool 5201 and a housing assembly5202. The spool 5201 is configured for the cutting line 510 a winding.At least a portion of the spool 5201 is arranged inside the housingassembly 5202, and the spool 5201 is rotatable with respect to thehousing assembly 5202 about a central axis 510 b. The first motor 530 isconfigured to drive the spool 5201 to rotate, and the second motor 540is configured to drive the housing assembly 5202 to rotate. A rotationalaxis of the first motor 530 is parallel to a rotational axis of thesecond motor 540.

The grass trimmer 510 further includes a driving gear 5208 and a drivengear 5209. The second motor 540 is configured to drive the driving gear5208 to rotate. The driving gear 5208 is engaged with the driven gear5209 to drive the driven gear 5209 to rotate. The driven gear 5209 iscoupled to the housing assembly 5202. The driven gear 5209 and thehousing assembly 5202 are synchronously rotated. In one example, thedriving gear 5208 includes a plurality of blades. The driving gear 5208is used as a fan to generate airflow for cooling the second motor 540.Similarly, the driven gear 5209 includes a plurality of blades. Thedriven gear 5209 is used as a fan to generate airflow for cooling thefirst motor 530.

In one example, the driven gear and the housing assembly are configuredto be a whole. That is, no driven gear is provided, and the housingassembly is formed with a gear engaged with the driving gear.

In one example, the housing assembly includes a plurality of blades, andis formed with a fan.

The grass trimmer 510 has an auto-winding mode and a cutting mode. Thecutting mode is a mode that the grass trimmer 510 is operated by theuser to perform the vegetation cutting operation. The auto-winding modeis a mode that the cutting line 510 a is automatically wound around thespool 5201 to complete the string winding without the user manuallyrotating the spool 5201 or the housing assembly 5202.

In the cutting mode, a rotational speed of the spool 5201 driven by thefirst motor 530 is the same as a rotational speed of the housingassembly 5202 driven by the second motor 540. A rotation direction ofthe spool 5201 is the same as a rotation direction of the housingassembly 5202. Under the driving of the first motor 530 and the secondmotor 540, the spool 5201 and the housing assembly 5202 aresynchronously rotated.

In the auto-winding mode, the spool 5201 is rotated with respect to thehousing assembly 5202, so that the cutting line 510 a is automaticallywound around the spool 5201. The housing assembly 5202 is formed with anouter aperture 520 b. When the cutting line 510 a wound around the spool5201 is used up, the user inserts the cutting line 510 a through theouter aperture 520 b of the housing assembly 5202, and fixes the cuttingline 510 a to the spool 5201. In the auto-winding mode, under thedriving of the first motor 530 and the second motor 540, the spool 5201and the housing assembly 5202 are relatively rotated, and the cuttingline 510 a is automatically wound around the spool 5201.

In one example, a rotational speed of the spool 5201 with respect to thehousing assembly 5202 in the auto-winding mode is less than a rotationalspeed of the spool 5201 in the cutting mode.

The rotational speed of the spool 5201 with respect to the housingassembly 5202 is a winding speed of the cutting line 510 a. The windingspeed of the cutting line 510 a is relatively low, which contributes tothe safety of the user's operation. The rotational speed of the spool5201 in the cutting mode is a rotational speed of the grass trimminghead 520. The rotational speed of the grass trimming head 520 isrelatively high, so that the efficiency of grass trimming is high.

In one example, in the cutting mode, the first motor 530 drives thespool 5201 to rotate along one direction. In the auto-winding mode, thefirst motor 530 drives the spool 5201 to rotate along a directionopposite to the one direction.

In another example, in the cutting mode, the first motor drives thespool to rotate along one direction. In the auto-winding mode, thesecond motor drives the housing assembly to rotate along the same onedirection, and the spool is still, so that the spool is rotated withrespect to the housing assembly.

In another example, in the cutting mode, the first motor drives thespool to rotate along one direction. In the auto-winding mode, the firstmotor drives the spool to rotate along the same one direction, and thesecond motor drives the housing assembly to rotate along the same onedirection. A rotational speed of the housing assembly driven by thesecond motor is greater than a rotational speed of the spool driven bythe first motor, so that the spool is rotated with respect to thehousing assembly.

The housing assembly 5202 is formed with the outer aperture 520 b, andthe cutting line 510 a can be inserted into the housing assembly 5202from the outside of the housing assembly 5202 through the outer aperture520 b. The spool 5201 is provided with the inner aperture 520 a for thecutting line 510 a trimming in. The housing assembly 5202 includes ahousing 5203 and an eyelet member 5206. The spool 5201 is accommodatedby the housing 5203. The eyelet member 5206 is formed with the outeraperture 520 b. The housing 5203 includes an upper housing 5204 and alower housing 5205. The spool 5201 is located between the upper housing5204 and the lower housing 5205.

In one example, the housing assembly includes the housing, and thehousing is formed with the outer aperture. That is, no eyelet member isprovided.

The grass trimmer 510 further includes a controller, and the controlleris configured to control the first motor 530 and the second motor 540 sothat the spool 5201 and the housing assembly 5202 can be stopped at aposition at which the inner aperture 520 a is aligned with the outeraperture 520 b. In one example, each of the first motor 530 and thesecond motor 540 is a brushless motor.

The control detects rotor positions of the first motor 530 and thesecond motor 540 and controls the first motor 530 and the second motor540 so as to align the outer aperture 520 b with the inner aperture 520a. The controller is arranged on the circuit board. In other words, thecontroller is composed of electrical components on the circuit board.

In one example, the grass trimmer 510 further includes a Hall sensordetecting a position of the spool 5201 or the housing assembly 5202, andan inductive controller controlling the first motor 530 and the secondmotor 540 to stop the spool 5201 and the housing 5203 at a position atwhich the inner aperture 520 a is aligned with the outer aperture 520 b.Based on the position of the spool 5201 and the position of the housing5203 detected by the Hall sensor, the inductive controller controls thefirst motor 530 and the second motor 540 to align the outer aperture 520b with the inner aperture 520 a.

When the user needs to wind the cutting line 510 a around the spool5201, the user can directly insert the cutting line 510 a into the inneraperture 520 a through the outer aperture 520 b. Then the user startsthe auto-winding mode, the spool 5201 and the housing assembly 5202 arerelatively rotated under the driving of the first motor 530 and thesecond motor 540, and the cutting line 510 a is automatically woundaround the spool 5201.

The grass trimmer 510 cuts the vegetation through the rotation of thecutting line 510 a protruding out of the grass trimming head 520. Whenthe grass trimmer 510 is in the cutting mode for a long time, thecutting line 510 a is in contact with the grass and is worn, causing thecutting line 510 being shortened. At this point, the user needs toincrease a length of the cutting line 510 a protruding out of thehousing assembly 5202.

The grass trimmer 510 also has a auto feeding mode. The rotationdirection of the spool 5201 with respect to the housing assembly 5202 inthe auto feeding mode is opposite to the rotation direction of the spool5201 with respect to the housing assembly 5202 in the auto-winding mode.The spool 5201 release portion of the cutting line 510 a wound aroundthe spool 5201, to increase the length of the cutting line 510 aprotruding out of the housing assembly 5202. The grass trimmer 510further includes a controller for controlling the spool 5201 to rotate apreset angle with respect to the housing assembly 5202 in the autofeeding mode.

In one example, the grass trimming head 520 may also release a certainlength of cutting line 510 a by a knocking manner. That is, the grasstrimmer 510 has a knock feeding mode. The spool 5201 is provided with afirst engaging tooth 520 c. The housing assembly 5202 is formed with afirst matching tooth 520 d matched with the first engaging tooth 520 c.The first engaging tooth 520 c and the first matching tooth 520 d arematched to release a desired length of cutting line 510 a. The grasstrimming head 520 further includes a spring 5207. The spring 5207applies an acting force between the lower housing 5205 and the spool5201, and is arranged between the lower housing 5205 and the spool 5201.

As shown in FIG. 42 to FIG. 52, a grass trimmer 610 includes a grasstrimming head 620, a motor 630, a connecting pipe 640, a handle 650 anda transmission mechanism 660.

The grass trimming head 620 is configured to mount or fix the cuttingline 610 a. The motor 630 is configured to drive the grass trimming head620 to rotate.

The handle 650 is configured for being gripped by the user. The grasstrimmer 610 includes a trigger 650 a for activating the motor 630. Thetrigger 650 a is arranged on the handle 650. When gripping the handle650, the user can operate the trigger 650 a to control the motor 630.The connecting pipe 640 is connected to the handle 650 and the grasstrimming head 620. The grass trimmer 610 further includes an auxiliaryhandle 650 b. The auxiliary handle 650 b is fixed to the connecting pipe640. In one example, the auxiliary handle 650 b is located between thegrass trimming head 620 and the handle 650. The user can grip the handle560 and the auxiliary handle 650 b by both hands respectively. In oneexample, the connecting pipe 640 has a hollow tubular structure, andsubstantially extends along a straight line.

The transmission mechanism is connected to the grass trimming head 620and the motor 630 so as to realize the motor 630 driving the grasstrimming head 620 to rotate.

The grass trimmer 610 further includes a power supply device forsupplying power to the motor 630. In one example, the power supplydevice is a battery pack 670. Of course, the power supply device may bea cable or an interface that is connected to an AC power supply networkor a battery.

The cable or the interface may supply the power of the AC power supplynetwork or the battery to the grass trimmer 610.

The grass trimmer 610 includes a main housing 680. The battery pack 670is fixed by the main housing 680. The battery pack 670 is detachablyconnected to the main housing 680. The main housing 680 is fixed to oneend of the connecting pipe 640. The grass trimmer 610 includes a circuitboard for controlling the motor 630. The circuit board is arrangedinside the main housing 680.

The grass trimmer 610 further includes a motor housing 690. The motor630 is accommodated by the motor housing 690. The motor housing 690 isfixed to another end of the connecting pipe 640. The connecting pipe 640is connected to the main housing 680 and the motor housing 690. Themotor housing 690 and the main housing 680 are fixed to two ends of theconnecting pipe 640 respectively. The motor 630 and the grass trimminghead 620 are located on a same end of the connecting pipe 640. Suchgrass trimmer 610 is generally referred to as a pre-motor 630 grasstrimmer 610.

In on example, the motor 630 and the grass trimming head 620 are locatedon two ends of the connecting pipe 640. Such grass trimmer 610 isgenerally referred to as a near-motor 630 grass trimmer 610.

The grass trimming head 620 includes a spool 6201 and a housing assembly6202. The spool 6201 is configured for the cutting line 610 a winding.At least a portion of the spool 6201 is arranged inside the housingassembly 6202 and rotatable with respect to the housing assembly 6202about a central axis 610 b.

The grass trimmer 610 has an auto-winding mode and a cutting mode. Thecutting mode is a mode that the grass trimmer 610 is operated by theuser to perform the vegetation cutting operation. The auto-winding modeis a mode that the cutting line 610 a is automatically wound around thespool 6201 to complete the string winding without the user manuallyrotating the spool 6201 or the housing assembly 6202.

In the cutting mode, the motor 630 drives the grass trimming head 620 torotate about the central axis 610 b. In one example, the motor 630drives the spool 6201 and the housing assembly 6202 to synchronouslyrotate.

In the auto-winding mode, the motor 630 drives the spool 6201 and thehousing assembly 6202 to relatively rotate to automatically wind thecutting line 610 a around the spool 6201. The housing assembly 602 isformed with an outer aperture. When the cutting line 610 a wound aroundthe spool 6201 is used up, the user inserts the cutting line 610 athrough the outer aperture of the housing assembly 6202, and fixes thecutting line 610 a to the spool 6201. In the auto-winding mode, thespool 6201 and the housing assembly 6202 are relatively rotated, and thecutting line 610 a is automatically wound around the spool 6201.

The transmission mechanism 660 includes a first output shaft 6601 and asecond output shaft 6602. The motor 630 drives the first output shaft6601 and the second output shaft 6602 to rotate. The motor shaft 6301simultaneously drives the first output shaft 6601 and the second outputshaft 6602 to rotate. The first output shaft 6601 drives the spool 6201to rotate, and the second output shaft 6602 drives the housing assembly6202 to rotate.

The transmission mechanism 660 has a first running state and a secondrunning state. When the transmission mechanism 660 is in the firstrunning state, a rotational speed of the spool 6201 driven by the firstoutput shaft 6601 is the same as a rotational speed of the housingassembly 6202 driven by the second output shaft 6602, and rotationdirections of the spool 6201 and the housing assembly 6202 are the same.The spool 6201 and the housing assembly 6202 are synchronously rotated,at this moment, the grass trimmer 610 is in the cutting mode.

When the transmission mechanism 660 is in the second running state, themotor 630 drives the spool 6201 and the housing assembly 6202 torelatively rotate so as to automatically wind the cutting line 610 aaround the spool 6201, and at this moment, the grass trimmer 610 is inthe auto-winding mode. In one example, when the transmission mechanism660 is in the second running state, the rotational speed of the spool6201 driven by the first output shaft 6601 is different from therotational speed of the housing assembly 6202 driven by the secondoutput shaft 6602.

In one example, a rotational speed of the spool 6201 with respect to thehousing assembly 6202 in the auto-winding mode is less than a rotationalspeed of the spool 6201 in the cutting mode. The rotational speed of thespool 6201 with respect to the housing assembly 6202 is a winding speedof the cutting line 610 a. The winding speed of the cutting line 610 ais relatively low, which contributes to the safety of the user'soperation. The rotational speed of the spool 6201 in the cutting mode isa rotational speed of the grass trimming head 620. The rotational speedof the grass trimming head 620 is relatively high, so that theefficiency of grass trimming is high.

In one example, the rotational speed of the spool 6201 in theauto-winding mode is less than the rotational speed of the spool 6201 inthe cutting mode. In the auto-winding mode, the rotational speeds of thespool 6201 and the housing assembly 6202 are relatively low, whichavoids the damages caused by the housing where the spool 6201 and thehousing assembly 6202 are accidentally touched by the user.

In the cutting mode, the first output shaft 6601 drives the spool 6201to rotate in one direction. In the auto-winding mode, the first outputshaft 6601 drives the spool 6201 to rotate in a direction opposite tothe one direction.

In one example, in the cutting mode, the motor 630 is rotated in aforward direction. In the auto-winding mode, the motor 630 is rotated ina reverse direction. The rotational speed of the motor 630 rotated inthe forward direction is greater than the rotational speed of the motor630 rotated in the reverse direction.

In one example, in the cutting mode, the first output shaft 6601 drivesthe spool 6201 to rotate in one direction. In the auto-winding mode, thefirst output shaft 6601 drives the spool 6201 to rotate in the same onedirection, and the second output shaft 6602 drives the housing assembly6202 to rotate in the same one direction; the rotation speed of thehousing assembly 6202 driven by the second output shaft 6602 is greaterthan the rotational speed of the spool 6201 driven by the first outputshaft 6601, so that the housing assembly 6202 and the spool 6201 arerelatively rotates to automatically wind the cutting line 610 a aroundthe spool 6201.

The grass trimmer 610 is provided with a function switching member 6615.The function switching member 6615 is movable between a first positionand a second position. When the function switching member 6615 is at thefirst position, the transmission mechanism 660 is in the first runningstate. When the function switching member 6615 is at the secondposition, the transmission mechanism 660 is in the second running state.

The transmission mechanism 660 further includes a first transmissiongear 6603, a second transmission gear 6604, a third transmission gear6605 and a fourth transmission gear 6606. The third transmission gear6605 and the first transmission gear 6603 are coaxially rotated, and thefourth transmission gear 6606 and the second transmission gear 6604 arecoaxially rotated.

The transmission mechanism 660 further includes a gear housing 6616, adriving gear 6607, a driven gear 6608, a first shaft coupling 6609, asecond shaft coupling 6610, a first drive gear 6611, a second drive gear6612, a first shaft 6613 and a second shaft 6614.

The first transmission gear 6603, the second transmission gear 6604, thethird transmission gear 6605, and the fourth transmission gear 6606 areaccommodated by the gear housing 6616. The driving gear 6607 is fixed tothe motor shaft 6301. The driving gear 6607 is engaged with the drivengear 6608 to drive the driven gear 6608 to rotate. The driven gear 6608is engaged with the first transmission gear 6603 to drive the firsttransmission gear 6603 and the third transmission gear 6605 to rotate.The first transmission gear 6603 and the third transmission gear 6605are fixed to the first shaft 6613. The second transmission gear 6604 andthe fourth transmission gear 6606 are fixed to the second shaft 6614.The second shaft 6614 is connected to the second output shaft 6602through the second shaft coupling 6610. The second 6614 is slidable withrespect to the second output shaft 6602. By the arrangement of the firstshaft coupling 6609, the second shaft 6614 and the second output shaft6602 may remain in a synchronous rotation. The first drive gear 6611 isfixed to the second output shaft 6602. The shaft 6301 is connected tothe first output shaft 6601 through the first shaft coupling 6609. Themotor shaft 6301 and the first output shaft 6601 are synchronouslyrotated.

In one example, no first shaft coupling is provided, and the firstoutput shaft and the motor shaft are configured to be a whole. In otherwords, the motor shaft is used as the first output shaft. A rotor of themotor drives the first output shaft to rotate.

When the function switching member 6615 is at the first position, thetransmission mechanism 660 is in the first running state. At thismoment, the motor 630 drives the first drive transmission gear 6603 andthe third transmission gear 6605 to rotate; the first transmission gear6603 and the second transmission gear 6604 are engaged; and the thirdtransmission gear 6605 and the fourth transmission gear 6606 areunengaged, so as to drive the second shaft 6614 to rotate. The secondshaft 6614 drives the second output shaft 6602 to rotate. The secondoutput shaft 6602 drives the first drive gear 6611 to rotate. The firstdrive gear 6611 is engaged with the second drive gear 6612 to drive thesecond drive gear 6612 to rotate. The first output shaft 6601 drives thespool 6201 to rotate. The spool 6201 and the housing assembly 6202 canremain in a synchronous rotation.

The second drive gear 6612 is coupled to the housing assembly 6202. Thesecond driving gear 6612 and the housing assembly 6202 are synchronouslyrotated. The housing assembly 6202 is slidable with respect to thesecond drive gear 6612 along a rotational axis, which ensures that thefirst drive gear 6611 and the second drive gear 6612 keep engaged whenthe user knocks the grass trimming head 620 to release the cutting line.In one example, the second drive gear 6612 is provided with a pluralityof fan blades. The second drive gear 6612 is used as a fan.

In one example, the housing assembly is provided with a plurality of fanblades.

When the auto-winding mode needs to be performed by the user, thefunction switching member 6615 is moved to the second position. Thethird transmission gear 6605 is engaged with the fourth transmissiongear 6606, and the first transmission gear 6603 is unengaged with thesecond transmission gear 6604, so that the motor 630 drives the secondshaft 6614. Since a transmission ratio of the third transmission gear6605 to the fourth transmission gear 6606 is different from atransmission ratio of the first transmission gear 6603 to the secondtransmission gear 6604, the rotational speed of the housing assembly6202 when the function switching member 6615 is at the second positionis different from the rotational speed of the housing assembly 6202 whenthe function switching member 6615 is at the first position. Since therotational speed of the spool 6201 when the function switching member6615 is at the first position is the same as the rotational speed of thespool 6201 when the function switching member 6615 is at the secondposition, the rotational speeds of the spool 6201 and the housingassembly 6202 are different when the function switching member 6615 isat the second position. The spool 6201 and the housing assembly 6202 arerelatively rotated to automatically wind the cutting line 610 a aroundthe spool 6201, realizing the automatic winding.

The basic principles, main features and advantages of the presentdisclosure have been shown and described above. It is to be understoodby any person skilled in the art that the foregoing examples are notintended to limit the present disclosure in any form. All technicalsolutions obtained by equivalent substitution or equivalenttransformation are within the scope of the present disclosure.

What is claimed is:
 1. A grass trimming head, comprising: a housingassembly, formed with a housing cavity and provided with an outeraperture for allowing a cutting line to be inserted from an outside ofthe housing assembly into the housing cavity; and a spool, at least aportion of which is arranged inside the housing cavity and which isrotatable with respect to the housing assembly about a central axis;wherein the spool is provided with an inner aperture for allowing thecutting line to be inserted into the spool or a clamping portionconfigured to fix the cutting line; wherein the spool comprises an upperspool portion and a lower spool portion, the upper spool portioncomprises an upper winding portion configured for winding the cuttingline, a first flange portion connected to an upper end of the upperwinding portion, and a second flange portion connected to a lower end ofthe upper winding portion, the lower spool portion comprises a lowerwinding portion configured for winding the cutting line, a third flangeportion connected to an upper end of the lower winding portion, and afourth flange portion connected to a lower end of the lower windingportion, and the upper spool portion is coupled to the lower spoolportion to form a line guide passage configured for the cutting line topass through the spool.
 2. The grass trimming head according to claim 1,wherein the line guide passage extends along a curved line.
 3. The grasstrimming head according to claim 1, wherein the upper spool portion iscoupled to the lower spool portion to form at least two line guidepassages intersected with each other.
 4. The grass trimming headaccording to claim 1, wherein the upper spool portion is coupled to thelower spool portion to form three line guide passages, any two of thethree line guide passages are intersected with each other, and the threeline guide passages are arranged around the central axis.
 5. The grasstrimming head according to claim 1, wherein the housing assemblycomprises an upper housing and a lower housing, the spool is arrangedbetween the upper housing and the lower housing, the lower housing isprovided with a protrusion portion protruding towards the upper housing,the lower spool portion is formed with a groove matched with theprotrusion portion, and the protrusion portion is matched with thegroove to guide the housing assembly to move with respect to the spoolalong the central axis.
 6. The grass trimming head according to claim 5,further comprising a bearing and a knocking cap, wherein the protrusionportion is formed with a mounting groove, the bearing is arranged insidethe mounting groove, and the bearing is connected to the knocking capand the lower housing.
 7. The grass trimming head according to claim 5,further comprising a spring, wherein the groove is arranged throughoutthe lower spool portion along the central axis, the spring protrudes outof the groove, and the spring is arranged between the upper spoolportion and the lower housing and configured to provide an acting forcecausing the upper spool portion and the lower housing to space apartfrom each other.
 8. The grass trimming head according to claim 5,wherein the upper housing is formed with a first matching tooth, thespool is formed with a first engaging tooth matched with the firstmatching tooth, and the first engaging tooth is formed with an inclinedsurface.
 9. The grass trimming head according to claim 1, furthercomprising an eyelet member, wherein the eyelet member is fixed to thehousing assembly and configured for the cutting line to pass throughfrom the housing assembly.
 10. The grass trimming head according toclaim 1, wherein the housing assembly comprises a housing and an eyeletmember, the housing is formed with the housing cavity, the eyelet memberis fixed to the housing and formed with the outer aperture, the spool isformed with the inner aperture, and a distance from the eyelet member tothe spool is less than or equal to 3 mm.
 11. The grass trimming headaccording to claim 10, wherein the second flange portion and the thirdflange portion cooperatively form a middle flange portion, the inneraperture is arranged on the middle flange portion, and a distance fromthe eyelet member to the middle flange portion is less than or equal to3 mm.
 12. The grass trimming head according to claim 11, wherein theeyelet member is formed with two bumps protruding towards the spool andthe two bumps are arranged on two sides of the outer aperturerespectively.
 13. The grass trimming head according to claim 12, whereinthe two bumps are arranged along a circumferential direction of thecentral axis and the two bumps are located between an upper surface anda lower surface of the middle flange portion along the central axis. 14.The grass trimming head according to claim 13, wherein the outeraperture is a waist-shaped hole, a size of the outer aperture along thecentral axis is defined as a height of the outer aperture, a size of theouter aperture along a direction perpendicular to the central axis isdefined as a width of the outer aperture, a size of the outer aperturealong an extending direction is defined as a depth of the outeraperture, a distance between the two bumps is the same as the width ofthe outer aperture, and the width of the outer aperture is greater thanthe height of the outer aperture.
 15. The grass trimming head accordingto claim 11, wherein the eyelet member is formed with a notch on oneside of a projection of the eyelet member on a plane perpendicular tothe central axis and the one side of the projection faces towards thespool.
 16. The grass trimming head according to claim 11, wherein adistance from the eyelet member to the middle flange portion is lessthan a maximum outer diameter of the cutting line.
 17. The grasstrimming head according to claim 1, further comprising a driving memberconfigured to apply an acting force to the housing assembly or thespool, wherein the acting force causes the housing assembly and thespool to relatively rotate, the spool has a line loading position withrespect to the housing assembly, in a condition that the spool is at theline loading position with respect to the housing assembly, the cuttingline can be directly inserted into the inner aperture or the clampingportion after passing through the outer aperture, the housing assemblyis formed with a first positioning surface, the spool is formed with asecond positioning surface matched with the first positioning surface,and, in a condition that one of the spool and the housing assembly isrotated with respect to the other to cause the first positioning surfaceand the second positioning surface to be in contact, the spool is at theline loading position.
 18. The grass trimming head according to theclaim 17, wherein the driving member is a spring, the spring is arrangedbetween the housing assembly and the spool and configured to apply theacting force to the spool or the housing assembly, and the acting forcecauses the first positioning surface and the second positioning surfaceto move toward each other.
 19. The grass trimming head according toclaim 18, wherein the housing assembly is formed with a plurality offirst matching teeth arranged around a circumferential direction of thecentral axis, the spool is formed with a plurality of first engagingteeth matched with the plurality of first matching teeth, the spring isconfigured to apply the acting force to the spool or the housingassembly, the acting force causes the first matching teeth and the firstengaging teeth to be in contact, each of the first matching teeth or thefirst engaging teeth is provided with an inclined surface inclined to asurface normal to the central axis, each of the first matching teeth isformed with the first positioning surface, each of the first engagingteeth is formed with the second positioning surface, and a number of thefirst engaging teeth is the same as a number of the inner aperture. 20.The grass trimming head according to claim 19, wherein in condition thatthe first positioning surface is in contact with the second positioningsurface, two sides of one of the first matching teeth is in contact withtwo adjacent ones of the first engaging teeth respectively, each of thefirst matching teeth is formed with a first inclined surface inclined tothe surface normal to the central axis, and each of the first engagingteeth is formed with a second inclined surface inclined to the surfacenormal to the central axis, the first inclined surface and the firstpositioning surface are located on two sides of a respective one of thefirst matching teeth respectively and the second inclined surface andthe second positioning surface are located on two sides of a respectiveone of the first engaging teeth respectively, and, in a condition thatthe first positioning surface is in contact with the second positioningsurface, the first inclined surface is in contact with the secondinclined surface.